The present invention relates to a control circuit for an air cleaner which has a function of performing automatic operation by detecting the pollution of the air in a room by a sensor.
As shown in FIGS. 1 to 3, a known air cleaner includes a casing 1 in which an electric fan 2 is incorporated. Air introduced into the casing 1 from suction ports 3 formed on a front face of the casing 1 passes through a prefilter 4 and then, is ionized by an opposite electrode 5 and a discharge wire 6. Subsequently, after dust has been removed from the air by a filter 7, the air is discharged from an exhaust vent 8. A remote control unit 9 is detachably mounted on an upper portion of the casing 1 and includes operating switches 10 and display portions 11. Furthermore, a gas sensor 12 for detecting the pollution of the air in a room is incorporated in the remote control unit 9. When the known air cleaner is set to an automatic operation mode by one of the operating switches 10, a detection circuit 13 receives an output of the gas sensor 12 and then, a control circuit 16, which is connected to an operation circuit 15 and a power source 14 for supplying electrical power to the electric fan 2 and between the opposite electrode 5 and the discharge wire 6, makes a decision on an output of the detection circuit 13 so as to control the power source 14 and a display circuit 17. Namely, automatic operation of the known air cleaner is operated in such a manner that the power source 14 and the display circuit 17 are turned on and off if the gas sensor 12 has detected that the air in the room is polluted and clean, respectively. Meanwhile, reference numeral 18 denotes a power cord.
The known air cleaner of the above described arrangement has been disadvantageous in actual use due to the fact that only the gas sensor 12 is employed as a sensor. Namely, in the case of a main application of the known air cleaner, such as the cleaning of the air at the time of smoking, the known air cleaner does not start its operation until smoke particles and gaseous matter generated from cigarettes reach the gas sensor 12 through their diffusion in the room after the cigarettes have been lit, thereby inevitably resulting in the necessity of a waiting time. Furthermore, the known air cleaner has a drawback in that since a heater portion is usually incorporated in the gas sensor, a waiting time of several minutes is required before a stable output of the gas sensor is obtained through the stabilization of temperature of the heater portion with the result that automatic operation of the known air cleaner cannot be performed during the waiting time.